Okay so you answered the important question at the very end of the video, what I need to see is a test just like this, but on pump gas, push the 706 heads with as much boost and timing as you can safely do, then swap on the 317 heads and see how much more boost you can safely run and how much more power the extra boost gives you, this is the question that we need answered.
This should be a big bang test! Get 2 sbe 5.3s with gapped rings, and keep turning up the boost too see what happens. Thank you for all the new content!
No, smaller engines have always responded better with smaller heads and tighter combustion chambers. It nothing new and want ever change. I really appreciate your no nonsense approach. These videos answer a lot of questions and you're the perfect guy for the job.
The next interesting stage to this test would be to mill down the 317 head to match compression of the 706 and see how much of an impact that intake valve size has in the n/a and boosted application.. Great video as always!
This is my thoughts exactly. The 706 heads provide much more compression over the 706 which have a much bigger cc, even bigger than the 243 which drops the compression dramatically. That combined with the proper cam with the right LSA and I bet the 317 will make better power and even torque at low end speeds.
The boost is lower on the 706 heads because the engine is swallowing the air. The heads are more efficient. Great videos.the best ‘ no bullshit’ back to back comparisons I have seen yet.
I was wondering the same thing. I’m trying to build a 6.0 ready for boost(can’t afford to go boost right now) and I don’t want to change it several times if I can help. So I second this comment. Same results with a 6.0 as the 5.3 had
The 5.3 with the 706 heads has about 9.5:1 compression. With the 317 heads that drops to 8:1 that's a big difference in comparison on the 5.3 ... I would like to see it on the 6.0 also
Do the same test on a 6.0. 20 pounds of boost , electronic boost controller , adjust each engine for maximum timing. I believe the increased timing on the low compression 317s will make more power.
Be careful saying something like this on the boosted lsx group on Facebook. You'll have about 20 people within 5 seconds calling you a dumbass. It's the blind leading the blind over there.
@@scottydoesntknow254 it just sucks at low rpm drivabily and for low boost. But with that said you don't have to drop the compression down a ton to gain from bring able to run more boost. 9.0:1 is still high enough to drive well, but will make more power than a stock compression motor.
Same test on a gen 3 6.0 please and possibly a few different boost levels gradually stepping up maybe mention Octane and Spark settings. Video lengths are just right!!
the only time I can see the higher compression being an issue is if you're running pump gas and you want to turn the boost up. It would be interesting to see which one would make more power before spark knocking. Tough test to perform though. Also be interesting to compare this cam to a good stage 2/3 turbo cam.
Hi Richard, thoughts on changing to 706 heads from 317s on my twin turbos 6.0 LQ4, 72 nova street/strip. I know compression will go up from 9.41 to about 10.5? Smaller chambers, 71 vs 61. Also any piston to valve clearance issues with my sloppy stage II cam 228/230, 585/585 lift, 706 heads on 6.0? I am always on e85. Any issues with changing the tune for timing etc on my holley terminator X? Holley guy told me terminator adjusts so fast reading o2 sensor and from my flex fuel sensor it almost instant adjusts tune from pure e85 to 91 octane added to fuel cell right away, so dont bother changing tune. Just asking for your experienced educated thoughts. Im sure lots of 6.0 guys thinking to change too since your dyno testing here! Many Thanks for all you do for us Richard showing us the real deal in all your dyno testing!!!
I have a set of PRC CNC'ED and decked 799's on my boosted .05 over ls6 half filled and they make great power iv had them on a sbe 4.8 and 5.3 also and went fast before the cnc porting they where just decked and they did pick up mph in the over 706s
@@richardholdener1727 I seen that one after I posted ,,, but would be nice to see a ported 706 with a 2.00 intake valve and a ported 243 on a 5.7 ...as I looking to put a 218/227 .600 lift cam in and while I'm at it up grading the heads too... but liking the port velocity of the 706 for tq down low i love your videos.. thats a lot of time you did on them to show us hot rodders
We learned what most knew already. The real test is how far can you push both heads on pump. The ONLY reason to drop compression is to run more boost. The test should be, is there a gain in safety factor on crappy pump fuel with the loss in efficiency that comes with the lower compression.
It could be different if you were octane limited at max effort. The 317 may allow more boost/ign. That would be something to try Richard. Obviously if using E85 or methanol id take the more compression of the 706.
The extra airflow comes into play when the displacement comes out to play. On a 6.0 you will notice a difference in the top end where the 317s will actually catch up and surpass the 706 heads. Depending on cam size it's usually over 6,000 RPM where this trade-off happens meaning the 706 head is still much better for average power production
@@richardholdener1727 your own videos contradict that. On a 6.0 with big cam the 706/862 looses like 10hp up top and gains 15-20 ft lbs below 5k in comparison to the same engine with 243/799 My own builds show the same result. On a 5.3 the 799/243 never surpasses the 706/862 at any rpm
Robert Ambrose then why do all the extra spending. The 862 beat the 243’s all around. If you’re not building a fire breathing 1200hp motor the regular 862 is the best head hands down. But if you want to throw away money then I guess you can
Nivlac57 this take aways would be the same the peak numbers would change. Compression is the key. They both flow good for the power levels. That’s why the 706/862 will win every time.
@@tysoncrandell9726 I believe further testing is required to make the determination. A 317 head will flow better on a 4 inch bore. On 3.78 bore, the valves are heavily shrouded with a 317 head. Therefore, I expect the the difference to be closer or the 317 to out perform the 706 at the same boost pressure. Don't know until you try.
I SEE A LOT OF COMMENTS TO MILL THE 317'S...BUT SINCE THOSE PEOPLE ARE NOT SMART ENOUGH TO UNDERSTAND THAT PURCHASING A PAIR OF 243'S WOULD BE LESS EXPENSIVE AND TO LAY THE BIG ARGUMENT TO REST...TEST THE 706 AGAINST THE 243 AS YOU DID IN THIS VIDEO HERE...HAPPY NEW YEAR!!!
I wonder, I have stock 5.3 heads and 4.8 flat tops pistons in a 5.3 with a ss2 cam running 18 psi. The extras compression from the pistons not being dished would be a good combo with the higher flowing 6.0 heads? Hmmmm....
I'd like to see one where you match the CR on a 317 equipped engine to the same as the 706 and then run it again. Given equal CR how would the extra flow of the 317 translate to power?
@@hendo337 Good point. How do these heads compare on a 6 liter is what I'm wondering. I have an lq4 I'll be putting into my 67 Camaro when it's done. I see lots of 6L swaps to rec port tests but what I would like to see is an lq4 at 10.75 ish -1 CR with a Sloppy Stage 2 or similar cam NA build.
Lower compression should be good for higher boost. Much higher. I'd also like to see the difference between big stroke/small bore vs small stroke/big bore. Same heads/cam/intake.
Richard Holdener I’m about to finish my 5.3 sbe with btr stage 4 turbo cam,prc 706 heads,Holley Hiram and S400 88/96 1.32ar. Drag car so with my converter won’t see under 4K from launch on so just hoping it will spool well 🤷🏼♂️
What if equal boost levels wasn't the goal but rather make the peak cylinder pressures made equal by using different boost levels. Would that be the point at which the 317s showed improvement with the greater flow? With lower compression wouldn't it take more boost on the 317s to equal the same peak cylinder pressures?
Richard I thought the 706 heads were prone to cracking, especially the ones that aren't made by GM, & outsourced by a different manufacturer, care elaborate on this issue, I just bought. a 133k mi LS junkyard 5.3 with the 706 heads on board, for a 95 OBS single cab Chevy 4.3 v6 5spd. man. swap as we speak. Anyhow... I love your knowledge & content on these LS engines got me excited and ready to get in my LS swap complete.✌👍👍
We've made 760 rwh on a chassis dyno with ported 317 heads, 8.3 to 1 compression , 21 degrees timing, E85, 14.5 lb of boost , 347 cubic inch, LS6 intake, twin 56 64 China turbos, China Air to air intercooler, 128 lb per hour injectors
At some point boost would overcome the compression deficit, and airflow would come into the equation, because boost is a measurement of restriction. Stick a mass airflow meter on it and measure the CFM of air going into the turbo, compare at that reference point instead of making boost the common factor, just a different way of thinking, measure base fuel consumption vs airflow vs power on the two sets of heads. Also lower compression makes the motor feel doggy when not in boost
From my perspective comparing both combo's at the same boost level misses the point of lowering the compression. If your higher compression engine isn't detonating you wouldn't lower the compression unless you were going to add boost. My question would be , if the high comp engine makes it best power with lets say 21 deg total timing then how much extra boost will the low comp combo take with the same 21 deg timing thus how much additional power will be delivered ?
I would I like to see this test done with both heads having to or relatively close compression and much better cam with a tighter lobe separation more suited for this engine combination. I’m willing to bet the motor will make more power up top and generate torque sooner at low speeds over the 706 heads.
the head test was done stock to stock-why would you change compression on 1 head to skew the test? A better cam will add power to both heads-but is not needed-the turbo determines the eventual power
@@richardholdener1727 the right or wrong cam will benefit one head while not benefiting the other, thus changing the results. Like I would do and I’m sure you would do is to make the most power NA before you put a power added on to make it easier to make power with less boost. This is just my opinion and how I see things. I would do this test and have both heads decked with the proper gasket deck height to make the same or as close to compression and have a custom cam built for each combination. The reason is that’s how I would do each combo to their max potentials for the street then boost from there. This being said I really do love your content and look forward to more of your content it’s always fair and unbiased I will be staying tuned I hope you consider my ideas for future builds. Keep up the good work.
I think the 317 heads would help with higher RPM hp. But based on this test in this RPM range the 706 heads won. As you said the boost dropped a tiny bit with the 706 heads vs the 317’s. Does that mean there was less restriction with the 706 heads in that RPM range since the boost controller wasn’t even touched.
i wonder how much more boost you can run on the 317 heads? 5-10 psi? How much more fuel would you need todo that? i would think on this set up you would have a motor failure long before the 317 heads made up any ground on the 706 heads. now put the 317 heads on a 400+ ci motor and it might be a little deferent
I'd like to see the test Maximizing boost for each head. In theory you should be able to run more boost with the 317 without the risk of detonation... maybe that's where you can make up the Power?
In theory we are led to believe that less compression is better for high boost numbers on pump gas, at what point would the 317 heads become an advantage? maybe 15psi and up? Please do this for us Richard Holdener.
It's going to take much more boost than that before it's a problem. It's not worth changing to the 317 heads. The air extra air flow is minimal on intake and about the same on the exhaust. Now sure you can run little more boost and timing with the 317s but the 706 is going to match the power just with less boost and timing. Which is a benefit if you happen to be running a blower. More boost with a blower the more heat becomes a problem. Many guys today run 10.1 or more compression. We've been running 11 to 12.1 for 20years. Specially in class racing where your limited to a particular size blower or turbo.
😂😂😂😂😂🤣🤣🤣🤣🤣 I found it!!!! Wish you turned that boost up more to about 15lbs. I now see what the better cam is. Didnt need top of the line intake and ported heads either
I’m wondering how the cam fits in as I understand you need to keep the overlap tight so the valves aren’t releasing loose out of the cylinder but with the different heads effect that as well as far as letting the air in and out because of the larger flow
I like the 706 heads. They're just a better size for the 5.3. The intake port has better air speed (better proportions for the 1.89" valve, especially with bowl porting), and the exhaust flows relatively more than the 317. The 317 needs a shorter duration cam to bleed off less compression, especially with the lower compression ratio.
Pity about the boost control situation, you could have taken on abother topic, being the effects of engine compression on turbo spool, seing as it was a decent sized turbo. It seems to be a popular one at the moment, and argued heavily. Airflow comes in more important at a higher effort combination. If you kept turning up the boost, the lower airflow heads will choke out, or the added compression will compound cylinder pressure enough under boost you cant run enough timing, egts will skyrocket and it will make less power.
The loss in power of the 317s is a combination of both compression and chamber turbulence. The 706 heads are designed for the smaller bore. If you changed pistons to bump the compression to the same with the 706 heads I think the 706 will still win NA as the turbulence would hurt it more than the extra flow would add. However, with boost and at the same compression, I think the numbers would be identical at low boost. But high boost the 317s would edge the 706s and will have more power potential at high boost. Your test proved the 317s flow more which is why boost increased.
Richard Holdener so if I am picking up what you’re putting down here, is it safe to say this test proves that more compression is worth much more than a few more cfm numbers at that power and boost level. So is cylinder pressure instead of cylinder filling more important since the more boost on 317s didn’t equate to more cylinder pressure. You would think by bumping the timing would narrow that difference because the 317s could accept a little more. But with all that said the 5.3 with 706 heads made more power NA than the 317s it “Should” in return make more under the same boost as well.
The cheap header comparison was great. Now a budget cam video would be nice to see... summit, Elgin, etc. Or even older designs, like a thunder racing cam....but use realistic street cams...not wild cam timing.
Master Mechanic what’s your setup on the 5.3. I’m building one just like it... 317 with vs 78/75 How does it do on bottom end and how much boost you running. What’s your numbers lol
Richard have you ever tested the 317s with different pistons to get the compression the same ? I'm curious if compression was the same if the 317s would make more power
I think the smaller valves on the 706 helped this 5.3, as they don't need bigger runners and valves like the 317 had , so the 706 heads weren't a choke point to that engine , a bigger engine would suffer from the 706 comparing to the 317 and then the 317 would outperform the 706.
I agree I would even like to see some 4.6/5.4 2 valve turbo testing. Now if he built a Cheap 460 stroker (514 inch) and ran some cheap aftermarket alloy heads with a pair of eBay GT45s I would be very interested because that is the engine I didn't build for my F150, I went stroker Windsor.
@Hakimbo Bola We could argue that one all day long if we were talking 30 year old engines, but when it comes to the LS, it's the strongest stock bottom end I've ever seen.
@@robertelmo7736 We are talking about durability. The LS is far superior to the Coyote in this regard. Just look up the frequency of broken pistons and spun rod bearings in the Coyote, it's a bit fragile.
I would like to see this same test on a boosted 6.0 LQ4 with 317 vs 706 heads. Why? Most budget guys get a 6.0 as an LQ4 with 317s, not the pricier motor rec port heads. So is it worth it to swap heads on a 6.0??? Why don't we ever see these tests on a 6.0 lq4 with 317s? Just seems that is what most budget guys get with a 6.0. So should they swap those 317 heads off at the extra expense? Thanks!
I'd like to know what the airflow gain was in CFM of the 317 heads over the 706? I think you did a video on this and I need to look back but clearly in this case compression was King. Maybe in a condition where 40cfm~ through the mid-range lift was the gain we might see the airflow balance out the power curves but in this case if we're only seeing a 10-15cfm swing between the two the flow just wasn't enough to overcome the increase cylinder pressure of the 706. I mean ultimately that's what it's about, right? Cylinder pressure... It's what makes power.
Great comparison. Were they tuned to the edge of knock for each combo or was each run on the same tune? It would be interesting to know how much overhead the lower compression buys in a real world situation, especially for 30 - 60 HP. I would think at higher boost levels, the higher comp motor would be octane limited, whereas the lower comp motor would have better chances of running without knock.
NA who said the gains are only from compression? the 317 heads have a smaller inlet valve and smaller port areas which are better suited to this cubic inch and rpm IMO which in itself normally results in VE improvements due to better velocity
@@richardholdener1727 yes thats what i meant. i mean i think part of gains are compression and part are the heads are actually sized better. the 706 v 799 NA showed this partly as the chamber vol are much closer to each other yet the smaller head still won
I would like to see a turbo cam shoot out between: Sloppy Stage II, Summit Racing Stage II, and BTR Stage II on a 6.0.
me too
Ooh that would be an awesome one.
and a 5.3 with 862 heads. Im leaning BTR
@@richardholdener1727 sloppy stage 1,2,3
So send Richard the cams and I bet he'd be happy to... lol
I’m so happy my lm7 has the 706s on it already 🥰
Okay so you answered the important question at the very end of the video, what I need to see is a test just like this, but on pump gas, push the 706 heads with as much boost and timing as you can safely do, then swap on the 317 heads and see how much more boost you can safely run and how much more power the extra boost gives you, this is the question that we need answered.
the 317s will make signifigantly more. You will be able to run double the boost or more where the 706s start detonating
This should be a big bang test! Get 2 sbe 5.3s with gapped rings, and keep turning up the boost too see what happens. Thank you for all the new content!
No, smaller engines have always responded better with smaller heads and tighter combustion chambers. It nothing new and want ever change. I really appreciate your no nonsense approach. These videos answer a lot of questions and you're the perfect guy for the job.
High boost + high compression = raging party.
Richard never apologize your videos are awesome. Keep up the good work👍
Richard you are the man. Thanks for doing these tests 🙏
The next interesting stage to this test would be to mill down the 317 head to match compression of the 706 and see how much of an impact that intake valve size has in the n/a and boosted application.. Great video as always!
He had a set i think , also had some ported 2" valve 706s
This is my thoughts exactly. The 706 heads provide much more compression over the 706 which have a much bigger cc, even bigger than the 243 which drops the compression dramatically. That combined with the proper cam with the right LSA and I bet the 317 will make better power and even torque at low end speeds.
YES, something like that.. @@thomasgjonovich5524
Stock bottom end LQ4, ported 317 heads, BTR stage 2 cam, E85, Bosch 210, 1200HP.
🤔🤔🤔 video of engine??
The boost is lower on the 706 heads because the engine is swallowing the air. The heads are more efficient. Great videos.the best ‘ no bullshit’ back to back comparisons I have seen yet.
Seemed like a lot of repetition of explanation, still a great vid. Would love to see a 317 v 706 with matching compression
Would be interesting to see if it would be the same on a 6.0
Compression beats flow with factory LS heads.
I was wondering the same thing. I’m trying to build a 6.0 ready for boost(can’t afford to go boost right now) and I don’t want to change it several times if I can help. So I second this comment. Same results with a 6.0 as the 5.3 had
@@TreyCovey just build what fits your budget and it really doesn't make that much difference
TreyCovey the 862 heads, same as the 706 will be best every time. Unless you’re building a 1200hp motor that is
The 5.3 with the 706 heads has about 9.5:1 compression. With the 317 heads that drops to 8:1 that's a big difference in comparison on the 5.3 ... I would like to see it on the 6.0 also
Please don’t ever apologize for anything ever again RH. You’d be giving us too much if it only had subtitles.
That cam is super efficient 👌
Turbo with vvt cams would be interesting to see what variable cam timing can do under boost
From what I've seen so far, most aftermarket cams require a VVT delete.
@@Borderline5440 Summit Racing has a series of VVT cams with use of Comp Cams timing reduction kit.
Love the longer videos
Do the same test on a 6.0. 20 pounds of boost , electronic boost controller , adjust each engine for maximum timing. I believe the increased timing on the low compression 317s will make more power.
Low compression sucks though. Low compression just gives you tuning adjustability
Be careful saying something like this on the boosted lsx group on Facebook. You'll have about 20 people within 5 seconds calling you a dumbass. It's the blind leading the blind over there.
@@scottydoesntknow254 it just sucks at low rpm drivabily and for low boost. But with that said you don't have to drop the compression down a ton to gain from bring able to run more boost. 9.0:1 is still high enough to drive well, but will make more power than a stock compression motor.
Keep up the good work Richard! These videos are great and packed full of info we all wonder!!
Compression for the win
Sweet comparison!!! What an eye opener...wow! Glad i subscribed!!
Thanks so much for making these videos ! You work your ass off so we can learn !!
I really liked this information, I have a 5.3 I want to run single turbo on pump gas as a daily driver, so please run the test with pump gas.
Same test on a gen 3 6.0 please and possibly a few different boost levels gradually stepping up maybe mention Octane and Spark settings.
Video lengths are just right!!
Now I want that engine with the cam, springs, ls6 intake and stock 706 heads for my project. Just NA will work for me.
Lookin better buddy.
You should do a test where you mill the 317 head to get same chamber sizes and see if the extra airflow on the 317 heads even makes a difference then.
Glad my 5.3 came 706's! Just gotta get it done.
So did mine checked last night and this video convinced me to keep them
the only time I can see the higher compression being an issue is if you're running pump gas and you want to turn the boost up. It would be interesting to see which one would make more power before spark knocking. Tough test to perform though. Also be interesting to compare this cam to a good stage 2/3 turbo cam.
Awesome info man, keep up the great work!
Hi Richard, thoughts on changing to 706 heads from 317s on my twin turbos 6.0 LQ4, 72 nova street/strip. I know compression will go up from 9.41 to about 10.5? Smaller chambers, 71 vs 61. Also any piston to valve clearance issues with my sloppy stage II cam 228/230, 585/585 lift, 706 heads on 6.0? I am always on e85. Any issues with changing the tune for timing etc on my holley terminator X? Holley guy told me terminator adjusts so fast reading o2 sensor and from my flex fuel sensor it almost instant adjusts tune from pure e85 to 91 octane added to fuel cell right away, so dont bother changing tune. Just asking for your experienced educated thoughts. Im sure lots of 6.0 guys thinking to change too since your dyno testing here! Many Thanks for all you do for us Richard showing us the real deal in all your dyno testing!!!
no change in p-v. should be clearance with that SS2 cam. not sure on timing change other than the 706 head wants a degree or two less NA
Thanks Richard!
Good information and testing once again! Thanks!
love the videos you make ... ALWAYS SO MUCH GREAT INFO .. 👍👍👍👍👍👍👍👍👍👍
I want to see the power difference between the two on 93 octain what makes more power befor detonation.
Your videos are awesome straight to the point and informative you just talk real fast in some vids
Thank you for all of this valuable information!
I have a set of PRC CNC'ED and decked 799's on my boosted .05 over ls6 half filled and they make great power iv had them on a sbe 4.8 and 5.3 also and went fast before the cnc porting they where just decked and they did pick up mph in the over 706s
Would love to see this test with the 243/799 heads in addition to the 706 and 317
Right on
great video... but like to see a ported 706 vs. a ported 317 head and or a 243 ported head video
THE PORTED 243 SHOULD HAVE THE MOST ABSOLUTE FLOW-CHECK OUT THE BIG LS HEAD TEST
@@richardholdener1727 I seen that one after I posted ,,, but would be nice to see a ported 706 with a 2.00 intake valve and a ported 243 on a 5.7 ...as I looking to put a 218/227 .600 lift cam in and while I'm at it up grading the heads too... but liking the port velocity of the 706 for tq down low
i love your videos.. thats a lot of time you did on them to show us hot rodders
Found it. Thanks.
We learned what most knew already. The real test is how far can you push both heads on pump. The ONLY reason to drop compression is to run more boost. The test should be, is there a gain in safety factor on crappy pump fuel with the loss in efficiency that comes with the lower compression.
It could be different if you were octane limited at max effort. The 317 may allow more boost/ign. That would be something to try Richard. Obviously if using E85 or methanol id take the more compression of the 706.
Need to test 317 or 706 on a 5.7. need a cheap upgrade😂
The extra airflow comes into play when the displacement comes out to play. On a 6.0 you will notice a difference in the top end where the 317s will actually catch up and surpass the 706 heads. Depending on cam size it's usually over 6,000 RPM where this trade-off happens meaning the 706 head is still much better for average power production
THE 317 NEVER PASSES THE 706-EVEN ON A 6.0L-IT HAS BEEN TESTED
@@richardholdener1727 your own videos contradict that. On a 6.0 with big cam the 706/862 looses like 10hp up top and gains 15-20 ft lbs below 5k in comparison to the same engine with 243/799 My own builds show the same result. On a 5.3 the 799/243 never surpasses the 706/862 at any rpm
what about the exact same test on a 6.0 and not a 5.3?
Robert Ambrose then why do all the extra spending. The 862 beat the 243’s all around. If you’re not building a fire breathing 1200hp motor the regular 862 is the best head hands down. But if you want to throw away money then I guess you can
I'd love to see this test on a 6.0L
Nivlac57 this take aways would be the same the peak numbers would change. Compression is the key. They both flow good for the power levels. That’s why the 706/862 will win every time.
@@tysoncrandell9726 I believe further testing is required to make the determination. A 317 head will flow better on a 4 inch bore. On 3.78 bore, the valves are heavily shrouded with a 317 head.
Therefore, I expect the the difference to be closer or the 317 to out perform the 706 at the same boost pressure. Don't know until you try.
I SEE A LOT OF COMMENTS TO MILL THE 317'S...BUT SINCE THOSE PEOPLE ARE NOT SMART ENOUGH TO UNDERSTAND THAT PURCHASING A PAIR OF 243'S WOULD BE LESS EXPENSIVE AND TO LAY THE BIG ARGUMENT TO REST...TEST THE 706 AGAINST THE 243 AS YOU DID IN THIS VIDEO HERE...HAPPY NEW YEAR!!!
I wanna see this test with matching combustion ratios to see what the better flow gets ya
I wonder, I have stock 5.3 heads and 4.8 flat tops pistons in a 5.3 with a ss2 cam running 18 psi. The extras compression from the pistons not being dished would be a good combo with the higher flowing 6.0 heads? Hmmmm....
I'd like to see one where you match the CR on a 317 equipped engine to the same as the 706 and then run it again. Given equal CR how would the extra flow of the 317 translate to power?
The extra flow is minimal and only on the intake side. They're very similar on the exhaust side. It's not worth the trouble.
@@hendo337 Good point. How do these heads compare on a 6 liter is what I'm wondering. I have an lq4 I'll be putting into my 67 Camaro when it's done. I see lots of 6L swaps to rec port tests but what I would like to see is an lq4 at 10.75 ish -1 CR with a Sloppy Stage 2 or similar cam NA build.
Lower compression should be good for higher boost. Much higher. I'd also like to see the difference between big stroke/small bore vs small stroke/big bore. Same heads/cam/intake.
can run the same amount in either.
@@Racestatus 40 lbs?
Chris Madsen my old 4cyl car use to run 60psi on 12.5 compression. It’s all in the tuning and fuel.
Can u please run this with same timing and turn up boost till you see knock on both combos and let us know what those boost limits were. The real data
I agree
Now lets see the pump gas limits on these different heads on the same motor. (stock cam and boost cam)
Love love love all your vids!!!!!! Keep it up! Ever try an S400 88/96 on a 5.3 ls?
only an S480 billet wheel
Richard Holdener I’m about to finish my 5.3 sbe with btr stage 4 turbo cam,prc 706 heads,Holley Hiram and S400 88/96 1.32ar. Drag car so with my converter won’t see under 4K from launch on so just hoping it will spool well 🤷🏼♂️
What if equal boost levels wasn't the goal but rather make the peak cylinder pressures made equal by using different boost levels. Would that be the point at which the 317s showed improvement with the greater flow? With lower compression wouldn't it take more boost on the 317s to equal the same peak cylinder pressures?
if we ran more boost on the 317s-they make more [pwer
Richard I thought the 706 heads were prone to cracking, especially the ones that aren't made by GM, & outsourced by a different manufacturer, care elaborate on this issue, I just bought. a 133k mi LS junkyard 5.3 with the 706 heads on board, for a 95 OBS single cab Chevy 4.3 v6 5spd. man. swap as we speak. Anyhow... I love your knowledge & content on these LS engines got me excited and ready to get in my LS swap complete.✌👍👍
We've made 760 rwh on a chassis dyno with ported 317 heads, 8.3 to 1 compression , 21 degrees timing, E85, 14.5 lb of boost , 347 cubic inch, LS6 intake, twin 56 64 China turbos, China Air to air intercooler, 128 lb per hour injectors
they work
At some point boost would overcome the compression deficit, and airflow would come into the equation, because boost is a measurement of restriction. Stick a mass airflow meter on it and measure the CFM of air going into the turbo, compare at that reference point instead of making boost the common factor, just a different way of thinking, measure base fuel consumption vs airflow vs power on the two sets of heads. Also lower compression makes the motor feel doggy when not in boost
He has spoken ...
From my perspective comparing both combo's at the same boost level misses the point of lowering the compression. If your higher compression engine isn't detonating you wouldn't lower the compression unless you were going to add boost.
My question would be , if the high comp engine makes it best power with lets say 21 deg total timing then how much extra boost will the low comp combo take with the same 21 deg timing thus how much additional power will be delivered ?
I would I like to see this test done with both heads having to or relatively close compression and much better cam with a tighter lobe separation more suited for this engine combination. I’m willing to bet the motor will make more power up top and generate torque sooner at low speeds over the 706 heads.
the head test was done stock to stock-why would you change compression on 1 head to skew the test? A better cam will add power to both heads-but is not needed-the turbo determines the eventual power
@@richardholdener1727 the right or wrong cam will benefit one head while not benefiting the other, thus changing the results. Like I would do and I’m sure you would do is to make the most power NA before you put a power added on to make it easier to make power with less boost. This is just my opinion and how I see things. I would do this test and have both heads decked with the proper gasket deck height to make the same or as close to compression and have a custom cam built for each combination. The reason is that’s how I would do each combo to their max potentials for the street then boost from there. This being said I really do love your content and look forward to more of your content it’s always fair and unbiased I will be staying tuned I hope you consider my ideas for future builds. Keep up the good work.
I think the 317 heads would help with higher RPM hp. But based on this test in this RPM range the 706 heads won. As you said the boost dropped a tiny bit with the 706 heads vs the 317’s. Does that mean there was less restriction with the 706 heads in that RPM range since the boost controller wasn’t even touched.
i wonder how much more boost you can run on the 317 heads? 5-10 psi? How much more fuel would you need todo that? i would think on this set up you would have a motor failure long before the 317 heads made up any ground on the 706 heads. now put the 317 heads on a 400+ ci motor and it might be a little deferent
Should just put a 3-5 lbs spring in the wastegate and don't boost reference it should do between 9-15 lbs everytime just based off back pressure
What was the compression ratio for each cylinder head combination?
I was looking for these video and found it . The 76/75 turbo what .a/r did it have
Octane is the deciding factor in head selection.
I'd like to see the test Maximizing boost for each head. In theory you should be able to run more boost with the 317 without the risk of detonation... maybe that's where you can make up the Power?
In theory we are led to believe that less compression is better for high boost numbers on pump gas, at what point would the 317 heads become an advantage? maybe 15psi and up? Please do this for us Richard Holdener.
It's going to take much more boost than that before it's a problem. It's not worth changing to the 317 heads. The air extra air flow is minimal on intake and about the same on the exhaust.
Now sure you can run little more boost and timing with the 317s but the 706 is going to match the power just with less boost and timing. Which is a benefit if you happen to be running a blower. More boost with a blower the more heat becomes a problem. Many guys today run 10.1 or more compression. We've been running 11 to 12.1 for 20years. Specially in class racing where your limited to a particular size blower or turbo.
Wayne Bollentin would it just the same not be worth switching “from 317’s” as that’s what came on my motor?
The extra air flow is affected by the coefficient of discharge. Flow testing each head would prove that it comes into play at some point.
😂😂😂😂😂🤣🤣🤣🤣🤣 I found it!!!! Wish you turned that boost up more to about 15lbs. I now see what the better cam is. Didnt need top of the line intake and ported heads either
I’m wondering how the cam fits in as I understand you need to keep the overlap tight so the valves aren’t releasing loose out of the cylinder but with the different heads effect that as well as far as letting the air in and out because of the larger flow
boost just multiplies what is there
I like the 706 heads. They're just a better size for the 5.3. The intake port has better air speed (better proportions for the 1.89" valve, especially with bowl porting), and the exhaust flows relatively more than the 317. The 317 needs a shorter duration cam to bleed off less compression, especially with the lower compression ratio.
Any fuel use info? I'm guessing higher compression is more fuel efficient🤔
efi should have some info somewhere
Which would be better for higher RPM and higher boost and lower compression ratio
I don't know, but we'll find out on the next installment of Richard the BOOST junky
Pity about the boost control situation, you could have taken on abother topic, being the effects of engine compression on turbo spool, seing as it was a decent sized turbo. It seems to be a popular one at the moment, and argued heavily.
Airflow comes in more important at a higher effort combination. If you kept turning up the boost, the lower airflow heads will choke out, or the added compression will compound cylinder pressure enough under boost you cant run enough timing, egts will skyrocket and it will make less power.
the motor made more power with the 706 heads-turbo spool will be improved
The loss in power of the 317s is a combination of both compression and chamber turbulence. The 706 heads are designed for the smaller bore. If you changed pistons to bump the compression to the same with the 706 heads I think the 706 will still win NA as the turbulence would hurt it more than the extra flow would add. However, with boost and at the same compression, I think the numbers would be identical at low boost. But high boost the 317s would edge the 706s and will have more power potential at high boost. Your test proved the 317s flow more which is why boost increased.
The change in boost was from the extra power offered by the 706 heads-which increased back pressure, which opened the waste gates earlier
Richard Holdener so if I am picking up what you’re putting down here, is it safe to say this test proves that more compression is worth much more than a few more cfm numbers at that power and boost level. So is cylinder pressure instead of cylinder filling more important since the more boost on 317s didn’t equate to more cylinder pressure. You would think by bumping the timing would narrow that difference because the 317s could accept a little more. But with all that said the 5.3 with 706 heads made more power NA than the 317s it “Should” in return make more under the same boost as well.
That’s good information I got the engine with 706 heads that I want to rebuild but I don’t have that much Experience to do it
The cheap header comparison was great.
Now a budget cam video would be nice to see... summit, Elgin, etc. Or even older designs, like a thunder racing cam....but use realistic street cams...not wild cam timing.
the SS2 (Elgin) cam has more intake duration than this cam
Richard you sound really sleepy at the 8:00 mark lol
You should try it
what was the compression for both heads? and what octane fuel was used?
I run 317 on my 5.3 and on e85 I am able to run 26 degrees so I think 317s come into play for being able to run more timing a d more boost safely
But if you can run less timing and less boost and make the same power then why not go that route? That's what make it an efficient engine.
Master Mechanic what’s your setup on the 5.3. I’m building one just like it... 317 with vs 78/75 How does it do on bottom end and how much boost you running. What’s your numbers lol
Richard have you ever tested the 317s with different pistons to get the compression the same ? I'm curious if compression was the same if the 317s would make more power
they won't on a 5.3L
Can you do this same test with the truck intake instead of the ls6? I bet it gets even better.
the tbss would be slightly better than LS6
I think the smaller valves on the 706 helped this 5.3, as they don't need bigger runners and valves like the 317 had , so the 706 heads weren't a choke point to that engine , a bigger engine would suffer from the 706 comparing to the 317 and then the 317 would outperform the 706.
the 317 have a big hurdle to over come before they make more power
I need this test done on a lq9 bottom end. I’m trying to figure out which head to use on mine.
Trick flow
Dont apologize we love the content brother but please more sbf guys !!
I agree I would even like to see some 4.6/5.4 2 valve turbo testing.
Now if he built a Cheap 460 stroker (514 inch) and ran some cheap aftermarket alloy heads with a pair of eBay GT45s I would be very interested because that is the engine I didn't build for my F150, I went stroker Windsor.
@Hakimbo Bola We could argue that one all day long if we were talking 30 year old engines, but when it comes to the LS, it's the strongest stock bottom end I've ever seen.
@@johnparrish9215 the toyota 1uzfe is pretty stout as bottom ends go as well.
The Ford is way stronger...not sure what you are talking about?
@@robertelmo7736 We are talking about durability. The LS is far superior to the Coyote in this regard. Just look up the frequency of broken pistons and spun rod bearings in the Coyote, it's a bit fragile.
Thanks, There’s a 5.3l block with 706 heads at my junkyard maybe I should pick it up.
I would like to see this same test on a boosted 6.0 LQ4 with 317 vs 706 heads. Why? Most budget guys get a 6.0 as an LQ4 with 317s, not the pricier motor rec port heads. So is it worth it to swap heads on a 6.0??? Why don't we ever see these tests on a 6.0 lq4 with 317s? Just seems that is what most budget guys get with a 6.0. So should they swap those 317 heads off at the extra expense? Thanks!
the result is the same-the 317 heads make less power than the 706 heads
Yes, greatly benefit of the street...😁
how about running it on lets say 16psi boost ?
*Pump Gas Shootout* 5.3 Low End Torque Truck Engine Maybe? 317's mild cam or anything designed for daily driver stock stall that runs on pump fuel.
I'd like to know what the airflow gain was in CFM of the 317 heads over the 706? I think you did a video on this and I need to look back but clearly in this case compression was King. Maybe in a condition where 40cfm~ through the mid-range lift was the gain we might see the airflow balance out the power curves but in this case if we're only seeing a 10-15cfm swing between the two the flow just wasn't enough to overcome the increase cylinder pressure of the 706. I mean ultimately that's what it's about, right? Cylinder pressure... It's what makes power.
Great comparison. Were they tuned to the edge of knock for each combo or was each run on the same tune? It would be interesting to know how much overhead the lower compression buys in a real world situation, especially for 30 - 60 HP. I would think at higher boost levels, the higher comp motor would be octane limited, whereas the lower comp motor would have better chances of running without knock.
Now take those 317’s and mill them down to match the 706 combustion chamber volume.
do you have a video that compares the 706 heads to the 862 heads?
THEY ARE THE SAME
How about if these 2 setups were tuned to the octane limit?
NA who said the gains are only from compression? the 317 heads have a smaller inlet valve and smaller port areas which are better suited to this cubic inch and rpm IMO which in itself normally results in VE improvements due to better velocity
I think you mean the 706 heads have those things, right?
@@richardholdener1727 yes thats what i meant. i mean i think part of gains are compression and part are the heads are actually sized better. the 706 v 799 NA showed this partly as the chamber vol are much closer to each other yet the smaller head still won